The present invention relates to a new composition of matter having antibacterial properties, Fortimicin C. The present invention also pertains to the production of Fortimicin C by culturing a Fortimicin C producing microorganism belonging to the genus Micromonospora in a nutrient medium until antibacterial activity is detected in the culture liquor and then isolating the active substance therefrom.
Antibiotics which exhibit activity against a broad spectrum of bacteria are always in demand. To this end, it has been found that when a strain of Micromonospora (hereinafter sometimes referred to as the MK-70 strain) isolated from the soil of the paddy field in Hiroshima Prefecture, Japan is cultured in a nuteint medium, several antibiotic substances are produced in the culture liquor. Among the active substances, two antibiotics, namely fortimicin B and A (which are respectively the subjects of the U.S. patent and patent application referred to above) were liberated. It has now been discovered that a third active substance is liberated by MK-70 strain, and this substance has been named Fortimicin C. A study of the chemical, physical and biological properties of this substance indicates that the composition of matter is a new antibiotic.